There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

How do you go from 98 to 720 using just one letter?

How many triangles are there in the picture below?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

Can you make a six-letter word using the letters N, A and B ?

Today, I celebrated my 32nd birthday but I was born in 1972.
How is this possible?

Identify the 10 differences between the two given pictures.

A mules travels the same distance daily.
I noticed that two of his legs travels 10km and the remaining two travels 12km.
Obviously two mules legs cannot be a 2km ahead of the other 2.

The mules is perfectly normal. So how come this be true ?

What is a word made up of 4 letters, yet is also made up of 3. Sometimes is written with 9 letters, and then with 4. Rarely consists of 6, and never is written with 5.

A boy and his father are caught in a traffic accident, and the father dies. Immediately the boy is rushed to a hospital, suffering from injuries. But the attending surgeon at the hospital, upon seeing the boy, says 'I cannot operate. This boy is my son.' How is this situation explained?